EMI shields are useful for many purposes, specifically for protecting forensic evidence. If a portable wireless device is taken from its owner it is important to ensure that the data on the device is not altered in any way from the point of seizure. One method of ensuring this is to shield the device from incoming or outgoing wireless signals using a portable EMI enclosure. It is often desirable to access the device inside of the EMI enclosure to forensically analyze the data it contains while keeping the evidence shielded from EMI signals. It may also be desirable to charge the device while inside of the EMI enclosure.
Prior to this invention, portable EMI enclosures did not provide a method for maintaining EMI shielding while accessing the device inside via cable for either data acquisition, charging, or both. Thus, there is a need for a method of accessing and connecting to a portable wireless device via cable while it is inside of a portable EMI enclosure, without compromising the shielding.
It is also desirable, or sometimes necessary, to manually operate a device inside of a portable EMI enclosure. Portable wireless devices with touchscreens are particularly problematic to operate inside of portable EMI enclosures. Thus, there is also a need for a method of operating portable wireless devices with touchscreens inside of portable EMI enclosures.
Portable EMI shields that allow one to preview devices contained therein shield EMI signals less effectively than portable EMI enclosures that do not allow one to preview the devices contained inside. This is most often noticed when transporting wireless devices inside of EMI enclosures. The reason why this is most often noticed during transport is because it is at this time that a portable wireless device could come close to a signal tower. The closer a wireless device is to a signal tower, the better chance it will have of connecting with the signal from that tower, rendering the EMI enclosure useless.
EMI enclosures that allow access to a device within the enclosure and shield signals effectively exist but they are not portable. They are heavy, metal-lined enclosures as in U.S. Pat. No. 5,594,200 to Ramsey.
Many prior art portable EMI enclosures do not allow cable access to a device inside without compromising their shielding. When operated correctly, they are bags that become a sealed container as in U.S. Pat. No. 7,601,921 to Shroader.
Also, prior art portable EMI enclosures do not allow a human to operate a touchscreen device inside, and prior art portable EMI enclosures that allow a preview of devices inside shield less effectively than portable EMI enclosures that do not allow preview.
Usage of touch screen devices inside of Faraday bags or other portable radio frequency shielding enclosures is difficult. The Faraday material (metalized fabric) is capacitive, therefore emulating the touch of a finger and contacting the device screen at multiple points. Solutions exist that provide methods of usage, but they are generally not efficient.
For example, one device includes a block of foam surrounding a touch screen device, which holds the Faraday material above the screen. A finger is pushed into the center of the foam, against the Faraday material, which contacts the screen at a single point. However, sliding a finger or another device across such an interface would be difficult.
In another device, a hard-sided RF shielding enclosure categorized as “non-portable” device is used. Although efficient, these methods are cumbersome. For example, a hard-sided RF shielding isolation box mated with two gloves allows the user to place his hands inside of the gloves, and is able to operate a device inside of the box. However, the gloves are double-layered, and form-fitting to a hand. They are not efficient to use on touch screens due to the one-size-fits-all glove format, which leaves loose fabric at fingertips for smaller hands. When extra fabric bunches at the fingertips, multiple points of contact are made on the device screen. The double layer of fabric adds to the problem by reducing the ability to accurately contact the screen.
In another device a user can place her hands inside of the Faraday box through a sleeve. Sleeves formed from Faraday material contact the user's arms directly. However, this system is not ideal as it offers the potential for radio frequencies to enter the box when the user's arms are removed from the sleeves.
Furthermore, none of the existing devices address the ability to open and close the RF shielding device to insert or remove additional devices to the shielding device without compromising an existing electronic device already in the shielding device. Current RF shielding enclosures, both portable and non-portable, are built with a single cavity. Devices placed inside of the cavity will no longer be shielded from signals when the cavity is reopened. This limits the ability of the operator to place other devices inside of the cavity, such as a stylus to operate the device more effectively, a battery to provide auxiliary power, or a forensic product that can extract information from the device.
Finally, current RF shielding enclosures, both portable and non-portable, are designed with a static form-factor. Non-portable enclosures are typically made with rigid materials, which are neither flexible nor expandable. Portable enclosures typically have two or three sides, which may be flexible, but not expandable. If an irregularly shaped object is placed inside of the enclosure, it may not fit correctly. Examples of these types of objects may be a phone with a power source connected to it, a router with antenna, or a tablet with a bulky case.